http://www.universetoday.com/122723...habitability-of-alien-exoplanets/#more-122723 More livable than Earth? New index sizes up the habitability of alien exoplanets by ALAN BOYLE on OCTOBER 5, 2015 Researchers at the University of Washington’s Virtual Planetary Laboratoryhave devised a new habitability index for judging how suitable alien planets might be for life, and the top prospects on their list are an Earthlike world called Kepler-442b and a yet-to-be confirmed planet known as KOI 3456.02. Those worlds both score higher than our own planet on the index: 0.955 for KOI 3456.02 and 0.836 for Kepler-442b, compared with 0.829 for Earth and 0.422 for Mars. The point of the exercise is to help scientists prioritize future targets for close-ups from NASA’s yet-to-be-launched James Webb Space Telescope and other instruments. Astronomers have detected more than 1,000 confirmed planets and almost 5,000 candidates beyond our solar system, with most of them found by NASA’s Kepler Space Telescope. More than 100 of those have been characterized as potentially habitable, and hundreds more are thought to be waiting in the wings. The Webb telescope is expected to start taking a closer look soon after its scheduled launch in 2018. “Basically, we’ve devised a way to take all the observational data that are available and develop a prioritization scheme,” UW astronomer Rory Barnes said Monday in a news release, “so that as we move into a time when there are hundreds of targets available, we might be able to say, ‘OK, that’s the one we want to start with.'” This isn’t the first habitability index to be devised. Traditionally, astronomers focus on how close a particular exoplanet’s mass is to Earth’s, and whether its orbit is in a “Goldilocks zone” where water could exist in liquid form. But in a paper accepted for publication in the Astrophysical Journal, Barnes and his colleagues say their scheme includes other factors such as a planet’s estimated rockiness and the eccentricity of its orbit. The formula could be tweaked even further in the future. “The power of the habitability index will grow as we learn more about exoplanets from both observations and theory,” said study co-author Victoria Meadows. Barnes, Meadows and UW research assistant Nicole Evans are the authors of “Comparative Habitability of Transiting Exoplanets.” The study was funded by the NASA Astrobiology Institute.
http://arxiv.org/pdf/1509.08922v1.pdf COMPARATIVE HABITABILITY OF TRANSITING EXOPLANETS Rory Barnes1,2,3, Victoria S. Meadows1,2, Nicole Evans1,2 Draft version October 1, 2015 ABSTRACT : Exoplanet habitability is traditionally assessed by comparing a planet’s semi-major axis to the location of its host star’s “habitable zone,” the shell around a star for which Earth-like planets can possess liquid surface water. The Kepler space telescope has discovered numerous planet candidates near the habitable zone, and many more are expected from missions such as K2, TESS and PLATO. These candidates often require significant follow-up observations for validation, so prioritizing planets for habitability from transit data has become an important aspect of the search for life in the universe. We propose a method to compare transiting planets for their potential to support life based on transit data, stellar properties and previously reported limits on planetary emitted flux. For a planet in radiative equilibrium, the emitted flux increases with eccentricity, but decreases with albedo. As these parameters are often unconstrained, there is an “eccentricity-albedo degeneracy” for the habitability of transiting exoplanets. Our method mitigates this degeneracy, includes a penalty for large-radius planets, uses terrestrial mass-radius relationships, and, when available, constraints on eccentricity to compute a number we call the “habitability index for transiting exoplanets” that represents the relative probability that an exoplanet could support liquid surface water. We calculate it for Kepler Objects of Interest and find that planets that receive between 60–90% of the Earth’s incident radiation, assuming circular orbits, are most likely to be habitable. Finally, we make predictions for the upcoming TESS and JWST missions.
We are born and bred of this spaceship "EARTH" We are a product of our shared co-evolutionary biom. To rank another planet higher than this one (for our needs) requires some serious justification........ Which i did not see. ergo "how silly of them". ..................
I had the same thought. Human beings evolved here on Earth. That implies that we are going to be highly adapted to conditions on this particular planet. 'Livability' in the sense of 'more pleasant for human beings' isn't just a matter of suitable temperatures and the possibility of liquid water, as important as those things undoubtedly are. There will have to be a breathable atmosphere and available food. I mean, what are the chances that an alien planet will have anything on it that humans can eat? (About zero, I'd say.) My impression is that the authors of this research were addressing a slightly different issue. They were thinking more in terms of identifying planets that are good candidates in the search for extraterrestrial life. They weren't thinking in terms of finding vacation planets that humans might find more enjoyable than Earth. An obvious difficulty there is that when considering the range of forms that alien life might take, science only has a sample size of one, namely Earth life. We don't even have a solid universally accepted definition of what the word 'life' means. It's usually defined ostensively, by pointing at examples of Earth life: 'Life is things with characteristics like that'. So searches for extraterrestrial life inevitably turn into searches for places where Earth life might be duplicated. (What we consider 'livable' might not impress a being that evolved in seas of liquid methane.)
Since the index was designed for "judging how suitable alien planets might be for life" not humans, you're criticizing them for claiming something that they aren't. While the title of the article may be misleading, that is the fault of the publication and not the researchers.
Even IF the index was based on "our needs" (which apparently it isn't), it doesn't follow that there couldn't be a place better suited to our needs. We evolved to fit the worst conditions on earth, not the best. A planet that was "all best" could justifiably be called "more habitable" than earth. We might not evolve in such a place to be as robust as we are here, but we could still inhabit such a place to better advantage than we inhabit earth.
agreed much of the time of genus homo evolved during this current ice age-------not the best of times nor climes. however we are not just one independent organism we are a collection of the millions of organisms that live in and on our bodies would we find the same (or suitable) symbiotic co-evolutionary organisms anywhere else?
I'm still doubtful about how much sense there is in saying that an exoplanet is "more livable than Earth". 'Just as livable as Earth' makes sense I guess, though it would probably be very hard to know that. There are just too many variables, too much that we don't really know about exoplanets. But how can a planet be more liveable than the one planet where we believe that life originated and where Earth life is perfectly adapted? I can certainly see ranking exoplanets in terms of the possibility of their being a suitable environment for Earth-type life. (Of course we don't know whether that's the only kind of life there is.) But Earth would seem to be the upper bound in that respect.
Even if an exoplanet has perfectly 'goldilocks' mass and orbital parameters, it will almost certainly lack the living environment, the plants, animals and microorganisms upon which we depend.
Wow! How some go off half cocked, missing completely the point being made. Let me supply an article that represents what this thread and the index are saying. Please Register or Log in to view the hidden image! Where to look for life by Staff WritersSeattle WA (SPX) Oct 08, 2015 Please Register or Log in to view the hidden image!UW astronomers Rory Barnes and Victoria Meadows of the Virtual Planetary Laboratory have created the "habitability index for transiting planets" to compare and rank exoplanets based on their likelihood of being habitable. Image courtesy Rory Barnes. Powerful telescopes are coming soon. Where exactly shall we point them? Astronomers with the University of Washington's Virtual Planetary Laboratory have created a way to compare and rank exoplanets to help prioritize which of the thousands discovered warrant close inspection in the search for life beyond Earth. The new metric, called the "habitability index for transiting planets," is introduced in a paper accepted for publication in the Astrophysical Journal by UW astronomy professors Rory Barnes and Victoria Meadows, with research assistant and co-author Nicole Evans. "Basically, we've devised a way to take all the observational data that are available and develop a prioritization scheme," said Barnes, "so that as we move into a time when there are hundreds of targets available, we might be able to say, 'OK, that's the one we want to start with.'" http://www.spacedaily.com/reports/Where_to_look_for_life_999.html extract: "This innovative step allows us to move beyond the two-dimensional habitable zone concept to generate a flexible framework for prioritization that can include multiple observable characteristics and factors that affect planetary habitability," Meadows said. "The power of the habitability index will grow as we learn more about exoplanets from both observations and theory."
Doesn't "bigger habitable zone" mean anything to a denizen of a planet like Earth whose major land masses are being rapidly deforested and converted into desert? Most species on this planet do not consider desert areas to be habitable, or they would be teaming with lush plant growth and animals other than sparse scrub brush and insects. Availability of liquid water is more conducive to life processes than dry desert wind and sand.
Wonderful. It's a valuable project and I applaud it. But it's already a certainty that life exists here on Earth. I don't see how any other planet could possibly rank higher than Earth in terms of its being a place to search for the existence of Earth-like life.
Because it's simply a scale of probabilities of what we already know, and to help and assist in future efforts to detect ETL. We only as yet have a sample of one where we know for certain. But based on all the aspects that are conducive to life as we know it, it is possible there is another planet that maybe more suitable for life [as we know it] than Earth. Actually the post previous to yours by Danshawen says it all.
Exo-Planets: More Livable than Earth: If so, lets send Marcy up there. He has proved that earthly mortals (barring of course few exceptions) are driven by FFF, Fame, Fund and F..k. Not necessarily in that order. The guys at Berkeley kept him despite knowing his inclination for third F, just because they were getting the second F. What a way to screw up ! An eye opener and restrain example for all others in academia.
